Secondary x-ray diaphragm and method of manufacturing the same



May 10, 1938. c` NIEMANN 2,115,637

SECONDARY X-RAY DIAPHRGM AND METHOD OF MANUFACTURING THE SAME Filed June 6, 1936 //V VEN To fi C 61A? L. /V /EM/q A/A/ Patented May 10, 1938 PATENT OFFICE SECONDARlY X-RAY DIAPHRGM AND METHOD OF MANUFACTURING THE SAME Carl Niemann, Erlangen, Germany, assignor to firm Siemens-Reiniger-Werke Aktiengesellschaft, Berlin, Germany Application June 6, 1936, Serial No. 83,952 In Germany June 8, `1935 3 Claims.

This invention relates to diaphragms for X-ray work and to methods of manufacturing the same, and refers more particularly to diaphragms used to intercept secondary X-rays.

Diaphragms for secondary X-rays used for medicinal purposes are usually placed between the patient and a photographic layer and consist of a large number of thin strips of an X-ray impervious material, such as lead, interconnected by a substance which transmits X-rays. Such diaphragms intercept secondary X-rays while transmitting primary X-rays to the photographic layer.

Practical experience has shown that it is eX- tremely difficult to manufacture diaphragms of this type. The strips of X-Aray impervious material are usually quite thin so that a single diaphragm may contain as many as one thousand of such strips. If all these strips are interconnected at one time, internal forces are apt to develop in them, causing a relative shifting of the strips. Obviously, such shifting is extremely undesirable, since when the diaphragm is finished, the shifted strips will produce a distorted X-ray picture, which may lead to incorrect diagnosis.

When the X-ray impervious strips are quite thin, for instance, when they have a thickness of a few tenths of a millimeter each, the manufacturing Idifliculties are increased still further. It is practically impossible, with methods known heretofore, to provide a diaphragm for secondary X-rays consisting of a large number of very thin ray-impervious strips which are directed toward the focal point of an X-ray tube situated at a predetermined distance from the diaphragm.

An object of the present invention is the provision of a diaphragm for secondary X-rays consisting of a large number of very thin X-ray impervious strips, all of which are situated in their proper relative positions.

Another object is the provision of a method of manufacturing diaphragms for secondary X-rays, by the useof which it is possible to obtain a diaphragm consisting of a very large number of very thin ray-impervious strips which are firmly and securely held in any desired respective positions.

The above and other objects of the present in vention may be realized through the provision of a method of manufacturing diaphragms-for secondary X-rays which comprises heating separately a ray-impervious strip (or a group of such strips), at least one of the surfaces of which was previously coated with a glue, such as adhesive wax or the like, which becomes soft when heated.

The heating is interrupted after the glue has (o1. 25o-e4) become soft. The `softened layer of glue carried bythe heated strip is maintained in contact with another strip and in the proper position relatively thereto, while the heated strip is allowed to cool. The layer of glue solidii'ies at the end of 5 the cooling period andrmly connects the two strips. Then the same procedure is repeatedwith other strips until a diaphragm is formed consisting of the desired number of strips.

The heated strip may be maintained in its proper position relatively to another strip only during the cooling period, or it may be placed in that position sometime prior to the beginning of the cooling period.

Each of the ray impervious strips may consist of one sheet of X-ray impervious material, such as lead, or it may comprise two layers, one of which is impervious to X-rays, while the other one transmits X-rays.

The invention will appear more clearly from the following detailed description when taken in connection with the accompanying drawing, showing by way of example, preferred embodiments of the inventive idea.

In the drawing:-

Figure 1 illustrates diagrammatically a method of heating the ray-impervious strips by means of an exteriorly located coil;

Figure 2 is a diagram illustrating a method of heating the strips by means of a current passing through the strips.

Figure 3 shows a diaphragm consisting of a plurality of ray-impervious strips interconnected by layersof glue; and

Figure 4 shows a diaphragm each of the strips of which consists of a layer of X-ray impervious material and a layer of a material transmitting X-rays, such strips being interconnected by layers of glue.

Figure 1 of the drawing shows a strip I0 consisting of X-ray impervious material, such as lead. The strips lil may have a length of about 400 mm., a thickness of` about 6.4 mm. The glue Il may have a thickness of about 0.1 mm., the strips maybe about 2 mm. in breadth. 45

. One side surface of the strip I0 is coated with a layer of `glue Il. The glue should be of the type which becomes soft after having been heated to a certain temperature. For instance, adhesive wax may be used. The adhesive wax becomes soft after having been heated to a temperature of about degrees (Celsius).

The strip l0 is held in the required position by a guiding device, such as a ruler I2. A suction device i3 is situated adjacent the ruler l2; 55

the device I3 is used to create air-suction, the force of which maintains the strip I0 in its proper position.

An elongated heating body such as an electrical wire Ill may be placed adjacent the strip I0. The heating wire I4 is supplied with an electrical current from a source of electrical energy I5.

The diaphragm is manufactured by placing a strip III having a layer of glue II upon the ruler I2 and maintaining it in the desired position by means of suction created by the suction device I3. Then the layer I I of the strip I Il is heated by means of the heating wire I4 until the layer of glue II becomes soft. Then the heating coil I4 is removed and another strip (not shown) is placed upon the heated layer II of the strip I0. Then the layer of glue II is allowed to solidify. The second strip may be pressed by hand against the iirst strip, although the force of suction created by the device I3 is usually sufficient to maintain proper contact.

It is possible to use artificial cooling means, such as a nozzle I6 blowing cold air upon the heated layer II to shorten the cooling period which must be continued until the glue becomes hard and firmly connects the two strips.

Then a third strip is joined to the two interconnected strips by the same method.

The method is repeated until a diaphragm of the desired dimensions is completed.

Figure 2 of the drawing shows an X-ray impervious strip II) coated with a layer of glue II and maintained in its proper position by means of a ruler I2 and a suction device I3. The strip I0 and the glue II are heated by an electrical current passing through the strip and supplied to it by the terminals II and I8 connected through the time switch I9 with a source of electrical energy I5.

The terminals II and I8 may be so constructed that they contact that strip which has already been treated, and which is permanently connected by a hardened layer of glue with an adjacent strip. On the other hand, in the construction shown in Fig. 2, the terminals I'I and I3 are placed in contact with a strip which is to be connected with another strip (not shown) by means of layer Il.

The time switch I9 which may consist of any suitable relay, is used for closing the circuit supplying the electrical current to the terminals I'I and I8 for a predetermined period of time and then automatically interrupting this circuit so that the strip I0 is heated by the electrical current during a predetermined period of time. This period of time should be just su'icient to heat one strip I Il and its layer II to the desired eX- tent.

A suitable variable resistance 2l) may be included in this circuit for the purpose of adjusting the strength of the heating current.

The manufacturing process is substantially the same as the one already described. First, a strip Il! is coated by alayer of glue II. The strip I0 is placed upon the ruler I2 and is maintained in its proper position upon that ruler by the suction device I3. Then the switch I 9 is closed and an electrical current of predetermined strength is caused to flow through that strip for a predetermined period of time. At the expiration of this period the device I9 is automatically switched oif, thus interrupting the circuit. Then a second strip (not shown) is placed over the first strip so that the softened layer of glue II contacts the adjacent surface of the unheated second strip.

Then the softened layer of glue is caused to solidify.

The blowing device I6 may be used to blow cold air upon the strips to cool the heated strip quickly and thus shorten the period of time during Which the layer of glue II solidiiies. At the end of the cooling period the layer of glue has completely hardened and it rmly connects the two strips.

Then the same process is repeated with a third strip, a fourth strip and so on until the desired number of strips are assembled and a completed diaphragm is formed.

The manufactured diaphragms are illustrated in Figures 3 and 4 of the drawing. Figure 3 shows a diaphragm consisting of several ray-impervious strips I which are connected with each other by layers of glue II. Figure 4 shows a diaphragm, each of the strips of which consist of two layers, viz, an X-ray impervious layer I0 and a layer 2| consisting of a material which transmits the X-rays. In this case also, all the strips are held together by layers of glue II.

In the described methods the strips have been connected individually one to the other. In some instances it may be advisable to connect the strips in sets of several strips at one time, such sets consisting of several strips which have been connected one with the other in any suitable manner.

What is claimed isz- 1. In a method of manufacturing diaphragms for secondary X-rays, the steps of coating at least one surface of a single strip which includes a layer of an X-ray impervious material with an adhesive substance, heating said strip until said adhesive substance becomes substantially soft, causing the softened adhesive substance to solidify, and maintaining said softened adhesive substance at least during the last-mentioned step in contact with a surface of another single strip which includes a layer of an X-ray impervious material, thereby iirmly interconnecting said two strips in their proper relative positions.

2. In a method of manufacturing diaphragms for secondary X-rays, the steps of coating at least one side surface of a single X-ray impervious strip with an adhesive substance which becomes soft when heated, passing an electrical current through said strip to heat said strip and soften said adhesive substance, then cooling said strip and maintaining it at least during the cooling period in a predetermined position adjacent one other strip, said adhesive substance contacting the last-mentioned strip during the cooling period and rmly interconnecting said strips at the expiration of the cooling period.

3. A diaphragm for secondary X-rays, comprising a plurality of strips, each of said strips comprising a layer of substantially X-ray impervious material; and layers of adhesive wax interconnecting said strips and firmly holding said strips in their respective positions relatively to each other.

CARL NIEMANN. 

